Calibration · Glossary

What is Accuracy?

% of span, reading or URLCalibration

Accuracy is how close a measurement is to the true value; in specifications it is the maximum expected error.

Accuracy Explained

Accuracy statements use different bases: % of span, % of reading or % of URL. These give very different errors at low readings, so always check the basis.

Total performance also includes temperature effects, static pressure effects, stability and installation.

Accuracy Formula

Error (% of span) = (Reading − True) ÷ Span × 100

Reading	instrument indication
True	reference value
Span	URV − LRV

Example: Range 0 to 10 bar, reference 5.00 bar, reading 5.03 bar: error = 0.3 % of span.

Calculators for Accuracy

CalculatorAccuracy Specification CalculatorFree online calculator with formula and worked example.CalculatorCalibration Error CalculatorFree online calculator with formula and worked example.CalculatorFlow Meter Accuracy CalculatorFree online calculator with formula and worked example.

Free Downloads

Free downloadTransmitter Accuracy Calculation ExcelFree download in Excel and PDF.Free downloadPressure Transmitter Calibration Report FormatFree download in Excel and PDF.

Frequently Asked Questions

What is Accuracy?

Accuracy is how close a measurement is to the true value; in specifications it is the maximum expected error.

Is accuracy the same as precision?

No. Precision is how closely repeated readings agree; an instrument can be precise but inaccurate.

Is ± 0.1 % of reading better than ± 0.1 % of span?

Yes, below full scale: at 10 % of span, % of reading gives a ten times smaller error.

Learn more on the blog

Instrumentation calibration and troubleshooting guide

A practical guide on instrumentationblog.in with more detail on accuracy and how it is applied on real plants.

Read Full Article

More Calibration Terms

Calibration termRepeatabilityRepeatability is the closeness of successive readings of the same input under the same conditions, same…Calibration termReproducibilityReproducibility is the closeness of results for the same quantity when conditions change, such as…Calibration termHysteresisHysteresis is the difference between readings at the same input when approached from below (upscale) and…Calibration termLinearityLinearity is how closely an instrument output follows a straight line between input and output; non…Calibration termZero and Span ErrorZero and span error describe an instrument whose reading is offset at the bottom of the range (zero) or…Calibration termMeasurement UncertaintyMeasurement uncertainty is a quantified range around a result within which the true value is expected to…

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